Messages in this thread | | | Subject | Re: [PATCH v2] checkpatch: add warning for unnecessary use of %h[xudi] and %hh[xudi] | From | Joe Perches <> | Date | Thu, 26 Nov 2020 01:28:15 -0800 |
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On Thu, 2020-11-26 at 14:16 +0530, Dwaipayan Ray wrote: > Modifiers %h and %hh should never be used. > > Commit cbacb5ab0aa0 ("docs: printk-formats: Stop encouraging use > of unnecessary %h[xudi] and %hh[xudi]") specifies that: > > "Standard integer promotion is already done and %hx and %hhx is useless > so do not encourage the use of %hh[xudi] or %h[xudi]." > > "The "h" and "hh" things should never be used. The only reason for them > being used if you have an "int", but you want to print it out as a > "char" (and honestly, that is a really bad reason, you'd be better off > just using a proper cast to make the code more obvious)." > > Add a new check to emit a warning on finding an unneeded use of %h or > %hh modifier. > > Link: https://lore.kernel.org/lkml/4910042649a4f3ab22fac93191b8c1fa0a2e17c3.camel@perches.com/ > > Suggested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com> > Signed-off-by: Dwaipayan Ray <dwaipayanray1@gmail.com> > --- > Changes in v2: > - Use $logFunctions instead of the manual list. > - Relocate the check to after logging continuations check. > - Remove perl_version_ok condition which is unneeded here. [] > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl [] > @@ -6027,6 +6027,18 @@ sub process { > "Avoid logging continuation uses where feasible\n" . $herecurr); > } > > +# check for unnecessary use of %h[xudi] and %hh[xudi] in logging functions > + if (defined $stat && > + $line =~ /\b$logFunctions\s*\(/) { > + my $lc = $stat =~ tr@\n@@; > + $lc = $lc + $linenr; > + my $stat_real = get_stat_real($linenr, $lc); > + if ($stat_real =~ /\"[^\"]*%[\d\.\*\-]*h+[idux].*\"/i) { > + WARN("UNNECESSARY_MODIFIER", > + "Unnecessary use of modifiers %h[xudi] or %hh[xudi]\n" . "$here\n$stat_real\n");
o Why not capture the group and show the actual integer format portion here? (%[\d\.\*\-]*h+[idux]) o This might also show every unnecessary use of %h. (using while (.../g) o The .*\" isn't useful. o The /i is probably wrong. o Perhaps this could use a --fix line if the format is on the same line as $logFunctions o Perhaps the message should say something about integer promotion. Maybe something like: "Integer promotion: using 'h' in '$1' is unnecessary\n"
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